PEORIA, Ariz. -- Mariners ace Felix Hernandez has taken things slowly so far this spring, as planned, but is expected to throw off a mound for the first time Wednesday with a 10-minute bullpen session.

Once Hernandez decided to opt out of the World Baseball Classic, the Mariners backed off his early Spring Training schedule to allow him extra time to prepare, particularly after he reported a few days late after flying to Seattle to sign his seven-year, $175 million contract extension.

Most of the other Mariners pitchers have thrown two bullpen sessions, plus one round of live batting practice, so Hernandez is about a week behind that schedule. But that's right where the Mariners want him at this juncture.

"We just need to get him ready by April," said pitching coach Carl Willis.

Hernandez will be the Opening Day pitcher against the A's in Oakland on April 1. Not so certain is who will start Friday's Cactus League opener, the annual charity game against the Padres at 1:05 p.m. MT (12:05 p.m. PT).

Manager Eric Wedge said he and Willis would be hammering out the pitching plans for the initial Cactus League games soon. At this point, all he could say is that each pitcher will throw one inning in the first game or two.

"You'll see a lot of guys out there," said Wedge.

Walker dazzles in first live batting practice

PEORIA, Ariz. -- Taijuan Walker threw his first live batting practice session of the spring on Tuesday and it didn't take long to remind folks why he's one of the top pitching prospects in baseball.

The 20-year-old right-hander has that certain sizzle to his pitches, the ball jumping out of his hand with the easy throwing motion that has scouts drooling. Walker hasn't pitched above the Double-A level yet, and thus is a longshot to break camp with the Mariners next month, but it's only a matter of time before he appears in Seattle's rotation.

"Very easy, very fluid, very effortless," said third baseman Kyle Seager, one of five Mariners hitters to face Walker on Tuesday. "The ball gets on you. He's got really good stuff."

With hitters just getting their timing down in the second day of live BP, no one got good wood on Walker's pitches. It's too early for that to mean much, with most hitters rarely even swinging yet against live pitching. But it's easy to see that Walker has electric stuff.

"He's stronger. He looks good," said manager Eric Wedge. "It was his first time out with hitters and what not, so you kind of keep your distance here early on. But the games are coming quick. So it was good to see him. It looked like he was throwing the ball well today.

"Obviously he has all the stuff. It's just a matter of him gaining more experience, getting more innings under his belt and working ahead."

Walker, ranked fifth in MLB.com's prospect rankings for 2013, said it was fun to just get back out on the field after a long offseason.

"It was good to face hitters again," he said. "Weird, because it's been a while. But it was good to see hitters in the box again."

Weather could put chill on Cactus League prep

PEORIA, Ariz. -- Weather in the Phoenix area has been perfect through the first week of Mariners camp, with blue skies and temperatures in the 70s, but the forecast for Wednesday is far more foreboding.

With 70 percent chance of rain and the temperature expected to be in the mid-40s when the team is scheduled to take the field at 9:30 a.m., manager Eric Wedge and his staff have been readying a backup plan.

The first Cactus League game is slated for Friday, and this year's tight early schedule doesn't leave much wiggle room for teams trying to get ready that quickly.

Pitchers have each thrown just one live batting practice after Tuesday's round of work, and hitters are just beginning to get their timing down against the live pitching, having just started full-squad workouts Saturday.

Pitchers are scheduled to throw once more -- half the group on Wednesday, the other half Thursday -- before the games begin. So a missed session now would wreak considerable havoc on the planning.

"We've been talking about it all day and we'll talk about it more here when everybody gets out of here," Wedge said after Tuesday's workout. "The priority has to be live BP. The guys that are supposed to throw tomorrow still need to throw.

"If we can't have hitters hit against them and we throw in the cage, we can still have people stand in. I'm not crazy about that. We'll get it done one way or the other, but it doesn't sound good for tomorrow."

As for the hitters' short preparation time for Friday's opener against the Padres, given they're only four days into their work?

"It is tough, but the guys knew that coming in and they've done a nice job here early on," Wedge said. "Friday is going to get on us quick and everybody is aware of that."

The Mariners' attitude? Bring it on.

"We are getting right into it," said Kyle Seager. "But that's a good thing. You get in there and start playing and it gives you more at-bats coming into the season. It's more time to get ready. There's nothing better than live pitching."

Worth noting

• Jon Garland and Jeremy Bonderman, two veteran pitchers coming back from arm problems, will throw their first live batting practice sessions on Wednesday.

• New radio announcer Aaron Goldsmith arrived at camp on Tuesday, joining Rick Rizzs as the Mariners broadcast team begins preparation for its first game on Friday. The three weekend games -- Friday, Saturday and Sunday -- against the Padres will all be broadcast live on 710 ESPN Seattle.

Then it will be radio silence for four games until 710 ESPN again picks up three games the following weekend. The first televised game on ROOT Sports will be Monday, March 4, against the Rockies at 12:05 p.m PT.

• Four of the final eight unsigned young Mariners players came to contract agreements Wednesday, with pitchers Carter Capps and Brandon Maurer, outfielder Michael Saunders and infielder Alex Liddi agreeing to terms. All players on the 40-man roster must be signed or renewed by March 11. The only unsigned players remaining are pitchers Stephen Pryor, Erasmo Ramirez and Tom Wilhelmsen and catcher Jesus Montero.